Identifying Niobium Minerals

Niobium, or columbium, as it is sometimes called, is a rare acid element that is associated with tantalum in the niobates and tantalates.

Reduction Test with Tin. The best test for niobium is to fuese some of the powdered mineral with several parts of sodium carbonate. The resulting mass is dissolved in a few cubic centimeters of dilute hydrochloric acid and the a few grains of metallic tin are added. The solution is boiled and the hydrogen set free bye the action of the acid on the tin serves as reducing agent. The result is to form a compound of niobium which is dark blue in color. This color does not readily change to brown on continued boiling, and disappears on addition of water. This distinguishes the niobium test from a similar one form tungsten.